Authorities allege that the friends went to Tsarnaev's dorm room at the University of Massachusetts-Dartmouth three days after the bombings, soon after the FBI posted photographs of the two bombing suspects, Tsarnaev and his older brother. The friends are accused in an indictment of removing several items from the room, including Tsarnaev's laptop computer and a backpack containing fireworks.

One friend, Robel Phillipos, 19, of Cambridge, was indicted last month on two counts of lying to authorities while he was being questioned. His lawyers declined to comment after the brief arraignment in U.S. District Court but said in a statement that Phillipos "had nothing to do whatsoever with the Boston Marathon bombing or destroying any evidence."

"In the end, it will be clear that this prosecution should never have been brought in the first place," attorneys Derege Demissie and Susan Church said in the statement.

Authorities allege that Tsarnaev, 20, and his brother Tamerlan, 26, ethnic Chechens from Russia, planned and carried out twin bombings near the finish of the marathon on April 15. Three people were killed and more than 260 were injured. Tamerlan Tsarnaev died in a gunbattle with police as authorities closed in on the brothers several days after the bombings.

Dias Kadyrbayev and Azamat Tazhayakov, both Kazakhstan nationals, are both charged with obstruction of justice and conspiracy to obstruct justice.

All four men attended the University of Massachusetts-Dartmouth.

Robert Stahl, an attorney for Kadyrbayev, said his client was "shocked and horrified" by the bombings and had "no intent" to obstruct justice.

"I'm saying he didn't dispose of evidence, didn't understand it was evidence, and the rest will come out at trial," Stahl told reporters after the arraignment.

More than two dozen family members and friends attended the hearing to support Phillipos. During an argument for bail in May, his lawyer portrayed him as a frightened and confused young man who was subjected to intense interrogation during the investigation.

Tazhayakov's parents and sister were in court during the brief arraignment. A translator said the family traveled from their native Kazakhstan in April and plans to remain in the United States until the case is resolved.

Tazhayakov's attorney, Nicholas Wooldridge, said the government "rushed into things" by charging his client.

"This is a witch hunt," Wooldridge told reporters after his arraignment.

All three men are due back in court Oct. 29 for a status conference.

Assistant U.S. Attorney John Capin said he expects to call about 20 witnesses during a two-week trial. No date has been set yet for it.